OAM Runtime SDK

NOTE: This SDK only support v0.1.x release of OAM specification (v1alpha1). For v0.2.x release (v1alpha2) please check KubeVela and its API lib repo kubevela-core-api as dependency.

The OAM Runtime SDK Project is a collection of go libraries and utility tools for building OAM runtime. With the SDK, we want to streamline and simplify building OAM runtime by achieving:

• Building new and converting to OAM API types easily.
• Reducing duplicate coding work via generating code scallfold and importing go library.
• Hiding low level details like k8s informer and providing high level abstraction to simplify user implementation.

Concepts

The SDK has the following major concepts that simplifies writing OAM code:

• Handler: A handler is an interface that must be user-implemented. The inputs and outputs are high level abstractions of events and actions.
• Event: An event is an encapsulation of change that triggers user handler. It could be events of k8s or other platforms (e.g. cloud MQ).
• Action: An action is an abstraction of declarative description of platform dependent operations. It separates concerns of high level user intention and low level platform details (e.g. client-go). In this way we have a modular system that provides reusable and pluggable actions.

The following diagram shows how they work together:

For more concepts in this SDK, please refer to concepts.md.

Getting started

There is an example implementation of OAM runtime using SDK in pkg/example/framework/main.go. We recommend reading the code as a starting point.

We could run the code and deploy OAM app by running following commands:

# turn on go module
export GO111MODULE=on

# install oam crds
make install

# run example
go run pkg/examples/framework/main.go

# deploy OAM component
kubectl apply -f examples/componentschematics.yaml

# deploy OAM app
kubectl apply -f examples/app.yaml

This example will create a deployment as Server workload.

There is another example which will show you how to build more extensions. Read the doc for more details.

Misc.

oam-runtime contains many utilities to help you implement oam runtime easier:

• finalizer

• status check

• spec equal check